Interlocking system for railroads



O. H. DICKE ET AL INTERLOCKING SYSTEM FOR RAILROADS May 14, 1940.

e Sheets-Sheet 1 Filed Oct. 31, 1932 H'chcock,

INVENTORS O.H.Dicke FB BY THEI ATTORNEY.

y 1940- o. H. DICKE ET AL 2,200,857

INTERLOCKING SYSTEM FOR RAILRQADS 7 Filed OCT. 31, 19:52 6 Sheets-Sheet2 INVENTORS THEIR ATTOR'NEY.

May 14,

3 3, 'mcKE Er A INVENTORS s Sheets-Sheets j o. H. DICKE Er AL V2,200,857 INTERLOCKING SYSTEM FOR RAILROADS Filed 001;. 31, 1932 6Sheets$heet 6 INVENTORS E *[I,".-'' g g HDiclffwEBHirchcoczk,

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55 .Such preconditioning of routes provides added tioned.

Patented May 14, 1940 UNITED STATES PAT NT, OFFICE INTERLOCKING SYSTEMFO nsmnoAns Oscar H. Dicke and Forest B. Hitchcock, Rochester, N. Y.,assignors to General Railway Signal Company, Rochester, N.' Y.

Application ctober 31, 1932, Serial No. 640,378

27 Claims. (01. 246-l34),.

This invention relates to interlocking systems facility at junctionpoints where it is desired to for railways, and more particularlypertains to have train movefn'e'nts occur as rapidly as possia system inwhich all of the interlocking between ble in accordance with thesignaling system, and the trafiic controlling devices is accomplished byyet not to require the instant attention of the circuit isolation.operator. 5

In one type of electric interlocking system, the The present inventionprovides these features setting up of a particular route through thetrack of preconditioning of routes in such a manner layout results inthe establishment of a route cirthat each switch individually respondsto its precuit which has circuit portions to conform prepositionedcontrol lever immediately after the cisely with the various mechanicalportions of the passage of a train over it although such train has 10-track layout. The route circuit, thus established, not entirely passedthrough the route over which is then employed for determining thedirection of it is traveling. In other words, rear release route trailicover the corresponding route by the polarc n s p ovid th a particular teis ity of its energization. set up by positioning its switches andclearing In systems of this character, it is further proits governingsignal, and this route cannot be 15 vided that the electrical routecircuit portions are changed once a train has passed beyond the govnotcompleted until the track switches in the 001- erning si a although, asthe train passes b responding route are actually looked. In other yond'each track switch included within that words, a lock relay, which isnormally energized route, that track switch is released so as to bewhenever it is safe for a track switch to be opoperated in response toits control lever in read- 20 erated,but is deenergized whenever atrackswitch in'ess for another route in which it may be inshould bemaintained in its last operated posicluded. v tion, is associated witheach track switch and is If desired, such rear releasing of a route mayprovided with back contacts that are included in be possible only afterthe return of the signal those electrical route circuit portions whichare control lever for that route to a stop position. 25 associated withthose routes that may be set up The present invention provides that theabove over the corresponding track switch. Such a feature may beemployed, but also provides that locking of the track switches, upon theclearing the rearrelease of a route may be accomplished of a signal whena route circuit has been comafter the automatic putting to stop of thegovernpleted, prevents the response of each track switch ing signal of aroute independently of the posiin that route to its control lever. tionof the signal control lever therefor.

It has previously been the practice to provide Other objects, purposesand characteristic feathat a track switch must be unlocked at the timetures of the present invention will be in part obof the actuation of itscontrol lever in order to vious from the drawings, and in part pointedout,

be operated to a new position. However, the presas thedescription of theinvention progresses. 35 ent invention provides what may be convenientlyIn describing'the invention in detail, reference termed preconditioningof routes, that is, when will be made to the accompanying drawings, in aparticular route has been set up, a conflicting which like referencecharacters designate correroute may be prepared or preconditioned bysponding parts throughout the several views, in

40 properly positioning the control levers therefor, which the likeletters insuch distinctive reference 40 although the correspondingtraffic controlling decharacters designate similar functions for thecorvices do not actually respond until a train has responding deviceswith the distinctiveness made passed through the first route or untilsuch route apparent by the use of distinctive preceding nuhas beenmanually restored. In a system of this merals, in which like numeralswhen applied to 5 character, the switch machine control levers fordistinctive lettersrepresent their inclusion withthe switches in aparticular route that is'set up, in a particular group of devices, andin which: may be operated to new positions while such Figs. 1, 2, 3A,33, 4A and 4B when considered switches are locked and when suchsWitches'betogether as hereinafter explained, constitute an comeunlocked, they will respond to the new pointerlocking system arranged inaccordance with sitions of their control levers. This prepositionthepresent invention as applied to a simple track 50 ingof the switchmachine control levers is aclayout including two cross-overs and asingle complished without in any way effecting a change turn-out; and inthe route circuit portions of the route already Fig. 5 illustrates amodified form which may be set up. i applied to the interlocking systemabove menhas been shown applied to a simple track. layout Fig. 1illustrates the track layout including the switches, switch machines andsignals, as well as the indicated switch control and indicationcircuits.

Fig. 2 illustrates the route circuit portions,

which conform to the mechanical layout of the trackway.

Figs. 3A and 33, when placed end to end, illustrate the locking circuitsfor the track switches. Figs. 4A andflB, when placed end to end, illus'trate the signal selecting circuits.

.For the purpose of further simplifying the illustration andfacilitating in the explanationv thereof, the various parts and circuitsconstituting the embodiment of the invention have been showndiagrammatically and certain conventional illustrations have beenemployed, the drawings having been made more with the purpose of mak ingit easy to understand the principles and mode of operation than. withthe idea of illustrating the specific construction and arrangement ofparts that would be employed in practice.

The various relays and their contacts are illustrated in a conventionalmanner and symbols are employed to indicate connections to the terminals of batteries or other suitable source of electric current insteadof showing all of the wire connections to these terminals.

7 The symbols and are employed to, indicate the positive and negativeterminals respectively of suitable batteries, or other sources ofelectric energy; and those circuits with which these symbols are usedare presumed to have cur-' rent flowing from the positive terminaldesignated by to the negative terminal designated by'Ihe-symbolsemployed with any one circuit presumably designate theterminals of the same battery, or other source. If alternating currentis employed, then these symbols should be considered to represent theinstantaneous, relative polarities of the respective terminals.

Armne'rus' In the accompanying drawings, the invention including astretch of double track having two cross-overs and one turn-out track;but it should be understood that the invention is not limited, as thusshown, to the control of the switches and signals of such a simplelayout, but may be extended for any desired number of switches andsignals and may be readily applied to all types ofv track layoutcommonly found in interlocking piants, junction points, terminals or anyother location where the routing of trains by a central operator. isdesired.

The stretch of double track includes a westbound track having tracksections 2 and 4, and an eastbound track having track sections 3, 5 andI. The track sections 2 and 3,-are interconnected by a cross-over havingtrack switches 2TS and 3T8; and similarly, the track sections 4 and 5are interconnected by a cross-over having track, switches lTS and 5T8.The track section. 1 is shown as having a track switch ITS forconnecting a turn-out track to the eastbound track. It

. in the patent to W. K. Howe, Patent No. 1,466,903

dated September 4, 1923. The switch machines are remotely controlled byan operator located in a tower through suitable control circuitsrepresented forthe purpose of the present disclosure by a dotted lineextending from the respective switch machine to its control lever in thetower, and may be controlled by aswitch control relay as shown inPatent'No. 2,027,569 referred to in the application of Larry et a1. Ser.No. 577,504, which application has now matured into Patent No. 2,125,242dated July 26, 1938. fically, the switch machines ZSM and 3SM are bothcontrolled by a switch machine control lever.

23SML; and similarly, the switch machines 48M and 58M are bothcontrolled by the switch machine control lever SSSML. The switch machine!SM is controlled by the switch machine More specicontrol lever 'ISML.Although the opposite ends of each cross-over are shown controlled fromasingle lever, in accordance with the usual practice, individual controlmay be employed'if de-' sired. The control circuits for the switchmachines may be of any suitable type which maybe interrupted for thelocking of the switch machines, but which upon their reclosure willimmediately allow the corresponding switch ma.

chine to respond to the then positions of their control levers.

It may be well to note here, that the type of 1 layout may be arrangedas desired, that is, the

layout may be of the usual interlocking type where the operator and thecontrolling apparatus are located at or adjacent the track layout,

or the arrangement may be of the remote type.

In actual practice, some of the'signal relays, devices and the like maybe located along the trackway, while other devices may be located in thetower, but for convenience in describing the present invention, it isassumed that the control levers for the switches and signals togetherwith their various associated controlling circuits and relays arelocated in the tower, and that suitable control circuits are providedfor remotely connecting thetower with the tramc controlling devices.Itis to be understood of course, that any suitable distribution of theapparatus may be made without affecting the system of the presentinvention in its operation and usefulness.

Although various signal arrangements might be provided for the tracklayout chosen for the embodiment of the present invention, the specificsignaling. arrangement chosen is illustrated in Fig. 1, where thesignals H and I3 govern the eastbound traflic over theeast and west maintracks, while the signals l2, I4 and I6 govern the westbound trafficover the east and west main tracks and the turn-out track respectively.These signals are indicated as being of the color light signal type butmay be of any other type,

or may beany other suitable signaling means for regulating trafiicmovements.

The control levers. are preferably mounted upon a suitable control panelwith indicating lamps, miniature track switches located on a trackdiagram and such other devices which may be associated with such acontrol panel to facilitate in the handling of traffic. On this controlpanel, the switch machine levers 23SML, 45SML and TSML (see Fig. 1) aresuitably located adjacent their corresponding miniature track switches(not shown) so as to readily identify the particular switches with whichthey are associated. Also, the signal levers IISL, I3SL, IZSL, MSL andiBSL (see Fig. 2) are suitably located on the control panel forgoverning their respective signals ll, l3, l2, l4 and 16 (see Figs. 1,4A and 4B).

The condition of occupancy of the various track sections 2, 4, 3, 5 andI are repeated in the tower by track relays 2T, 4T, 3T, 5T and ITrespectively see Fig. 1). In other words, the track relays are indicatedby the letter reference character T and indicated as being associatedwith their respective track sections as designated by the precedingnumerals. The track sections into which the track has been divided areassumed to have track circuits of the closed circuit type, so that thetrack relays are normally picked up or energized.

The position of the track switches is indicated in the tower by theprovision of suitable switch repeating relays indicated by the referencecharacters WP and associated with the particular track switches asindicated by their preceding numerals (see Fig. 1). For example, as thetrack switches 2TS and 3TS are both controlled by the switch'machinelever 23SML, only one switch repeating relay 23W? is required, which ofcourse, is dependent upon both of the track switches 2TS and 3TS beingin corresponding locked positions. Each switch repeating relay WP is of'the polar neutral type and is energized with a current of a particularpolarity depending upon the particular position and locked condition ofits corresponding track switch or switches, and whenever a track switchis unlocked, the corresponding switch repeating relay WP is deenergized.For convenience, it is assumed that the track switches are in theirnormal positions and locked so as to energize the switch repeatingrelays WP with suitable potentials to actuate their polar contacts toright hand positions and to actuate their neutral contacts to energizedposi-. tions.

' The switch repeating relays WP are associated with their respectiveswitch control levers in such a manner that a correspondence relay isprovided for each switch control lever (see Fig. 1). Thesecorrespondence relays are'represented by the letter reference charactersCR and are associated with the particular track switch and control leveras indicated by their preceding numerals. These correspondence relaysare of the usual neutral type.

Each of the signal control levers SL is provided with a lever repeatingrelay designated by the letter reference character SLP and associatedwith the particular lever as indicated by the preceding numeral (seeFig; 2). Also, associated with each signal lever is a route relaydesignated by the letter reference characters RR and indicated asassociated with the corresponding signal leverby its preceding numeral.

Associated with each track section between opposing signals are twodirectional stick relays, one for eastbound traffic and the other forwestbound traffic. More specifically, the east and west stick relays aredesignated by the letter reference characters ES and WS respectivelywith suitable preceding numerals to designate the particular tracksections with which they are associated (see Figs. 3A and 3B). Thesedirectional stick relays provide the route looking for the trackswitches together with the rear releasing of such track switches uponthe passage of a train over each track switch individually.

A look relay designated by the letter reference characters LR isassociated with each track switch as indicated by their precedingnumerals. These locking relays LR are normally energized but whenever aroute is set up and the signal therefor has been cleared, the lockrelays for the track sections in such route are deenergized preventingthe control of their corresponding track switch machines by theircontrol levers (see Fig. 1).

In accordance with the present invention, it is contemplated thatsuitable approach locking and time release therefor may be associatedwith each of the signals, if desired. This has been indicated in thedrawings by jumpers given the reference characters TL with suitablepreceding numerals to designate the signals with which they areassociated (see Figs. 3A and 3B). In other words, these jumpers TL maybe considered as time locking contacts which are opened whenever thecorresponding signal is cleared and closed only a predetermined timeafter such signal has been put to stop providing there is a train inadvance of said signal. If however, there is no train in advance of aparticular signal, the time looking contact TL for that signal closesimmediately upon the putting to stop of that signal. Such approachlocking and time releasing therefor has been shown in numerousapplications, as for example, in the application of Larry et al.', Ser.No. 577,504, filed November 27, 1931, now Patent No. 2,125,242 datedJuly 26, 1938. Although suitable points of insertion for suitableapproach loclnng having been illustrated,- the operation of such lockingand time release therefor will be omitted in the description of thepresent embodiment.

Each of the signals is controlled by its respective home relay HR whichis selected by the signal lever repeating relays, route relays, trackrelays and switch repeating relays. The particular signal with which arelay HR is associated is indicated by its preceding numeral (see Figs.4A and 4B). 1

In the modified form of the present invention illustrated in Fig. 5, atrack repeating stick relay TPS is provided and is indicated as beingfor the track section 3 by making its reference character 3TPS. Inconsidering the modified features in Fig. 5, it is to be understood thatthe arrangement shown is only a fragmentary part of the system intendedto be disclosed, and that the remaining corresponding parts of theembodiment shown in Figs. 1, 2, 3A, 313, 4A and 43 should be similarlyarranged and modified in order to accomplish the features provided inconnection with this modified form.

It is believed that the characteristic features and purposes of thepresent invention will be best understood by further description beinggiven from the standpoint of typical operations.

OPERATION Normal conditions.-Although the track switches T5 are usuallyleft in their last opertheir respective switch machine control levers'lay "IE6 is closed from through a circuit f normal positions.

SML. The signal control levers SL, however, are usually returned tonormal at-stop positions, as shown, so that the corresponding signalsdisplay stop indications. Y

With the track sections unoccupied, the track relays T are normallyenergized with their contacts picked up, which condition has been merelyindicated in the drawings.

The switch repeating relays WP are energized in accordance with thenormal positions of their respective track switches TS, as abovementioned.

As the signal control levers SL are all in their at-stop positions andthe track sections are unoccupied, the pick-up circuits and stickcircuits for all of the directional stick relays are closed, as pointedout below (see Figs. 3A and 3B).

A pick-up circuit for the directional stick relay 2ES is closed fromthrough a circuit including front contact. of relay 3E3, time lookingcontact I 3TL, back contact 26 of relay I3SLP, front contact 27 of trackrelay 2T, windings of relay 2E8, to An auxiliary stick circuit for thisrelay ZES is closed by its front contact 28 completing a shunt circuitaround the front contact 21 of the track relay 2T. A holding circuit forrelay 2E8 is closed from through front contact 29 of relay 23WP, polarcontact 39 of relay 23WP in a right hand position, around the contact 25of relay 3E8 to render it. ineffective to control the relay- 2E8 whenthe track switches ZTS and 3TS are in A pick-up circuit for thedirectional stick relay 4E8 is closed from through a circuit includingfront contact 3| of relay ZE'S, wire 32, front contact 33 of relay 4T,windings of relay 4ES, to 4E8 is closed by its front contact 34completing a shunt circuit around the front contact 33 of the trackrelay 4T.

A pick-up circuit for the directional stick relay 3E3 is closed fromthrough a circuit including the time looking contact IITL, back contact46 of relay IISLP, front contact 41 of relay 3T, windings of relay 3E8,to An auxiliary stick circuit for this directional stick relay3ES \isclosed by its front contact 48 completing'a shunt circuit around thefront contact 41 of track relay 3T.

A pick-up circuit for the directional stick relay 5E8 is closed fromthrough a circuit including front contact 35 of relay 3ES, wire 4|,front contact 36 of relay 4E8, front contact 31 of relay 5T, windings ofrelay 5ES, to An auxiliary stick circuit for this directional stickrelay 5E8- is closed by its front contact completing a shunt circuitaround the front contact 31 of the track relay ET. A holding circuit forrelay 5E3 is closed by the front contact 38 of relay W? and the polarcontact 39 of relay 45WP in a right hand position completing a shuntcircuit around front contact 36 of relay 4E8 to render the relay dESineffective to control the relay 5E3 when the track switches ETS and 5T3are in normal positions.

A pick-up circuit for the directional stick reincluding front contact 42of relay 5E8, front contact 43of track relay 1T, windings of relay Anauxiliary stick circuit for this relay An auxiliary stick circuit forthis directional stick relay TES is closed'b-y its front.

contact 44 completing a shunt circuit around the front contact 43 of thetrack relay 1T.

A pick-up circuit for the directional stick.

relay 4W8 is closed from through a circuit including closed time lookingcontact I2TL, back contact 49 of relay I2SLP, front contact 50 of relay5WS, front contact 5| of track relay 4T, windings of relay iWS, to Anauxiliary stick circuit for this directional stick relay 4W8 is closedby its front contact 52 completing a shunt circuit around thefrontcontact 5| of the track relay 4T. A holding stick circuit for relay4WS is closed by the front contact 53 of relay 45WP and the polarcontact 54 of relay 45WP in a right hand position completing a shuntcircuit around front contact 50 of relay 5W8 to render the relay 5W8ineffective to control the relay 4W8 when the track switches 4T5 and 5T8are in normal positions.

A pick-up circuit for the directional stick relay ZWS is closed fromthrough a circuitv including front contact 55 of relay 4WS, wire 56,front contact 51 of relay 2T, windings of relay ZWS, to directionalrelay 2WS- is closed by its front con- An auxiliary stick circuit forthis tact 58 completing a shunt circuit around the lay 5WS is closedfrom through a circuit:

including front contact 68 of relay TWS, front contact 69 of track relay5T, windings of relay 5WS, to'() An auxiliary stickcircuit for thisdirectional stick relay 5WS is closed by its front contact 10 completinga shunt circuit around the front contact 69 of the track relay ST.

A pick-upcircuit for the directional stick relay 3WS is closed fromthrough a circuit including front contact 59 of relay 5W8, wire 60,

front contact SI of relay ZWS, front contact 62 of relay 3T, windings ofrelay 3W3, to An auxiliary stick circuit for this relay 3WS isclosed byits front contact 63 completing a shunt cire cuit around the frontcontact 52 of the track relay 3T. A holding circuit for the relay 3WS isclosed by the front contact 64 of relay 23WP and the polar contact 65 ofrelay 23WP in its right hand position completing a shunt circuit aroundfront contact 6] of relay ZWS to render the relay 2WS ineffective tocontrol the relay 3W8 when the track switches ZTS and 3T5 are in normalpositions. I v I An energizing circuit for the lock relay 23LR is closedfrom through a circuit including y front contact 15 of relay 3W8, frontcontact 16 of relay ZWS, front contact 1'! of relay 2T, front contact 18of relay 3T, front contact 13 of relay f ZES, front contact of relay3E8, windings of relay 23LR, to Y An energizing circuit for the lockrelay 45LR is closed from through a circuit including front contact 8|of relay 5W8, front contact '82 of relay GWS, front contact 83 of relay4T, front contact 84 of relay 5T, front contact 85 of relay 4E8, frontcontact 85 of relay 5E8, windings of relay 45LR, to

An energizing circuit for the lock relay ILR. is closed from through acircuit including front contact 81 of relay 'IWS, front contact 88 ofrelay 1T, front contact 89 of relay IES, windingsof relay 'ILR, to

n With the signal control levers in their at-stop positions, theircorresponding signals display stopindications. As the signals have beenillustrated as being of the light signal type, the red indicator lamp Rof each signal is energized through a back contact of its correspondingrelay HR, while the green indicator lamp G of each signal is deenergized(see Figs. 4A and 43). For example, the red or stop lamp of the signal His energized by a circuit from through a circuit including back contact90 of relay I ll-IR, indicator lamp R, to

As the trackswitches are in correspondence with their respective controllevers, their respective correspondence relays are normally energizedisee Fig. 1). For example, the correspondence relayZSCR is energized bya circuit closed from .(-l-)., through a circuit including contact 9| ofswitch machine control lever 23SML in a normal position, polar contact92 of relay 23W'P in a right hand position, front contact 93 of relay23WP, windingsof relay 23CR, to I The correspondence relay 450R isenergized by a circuit closed from through a circuit ine cluding contact94 of switch machine control lever ASSML in a normal position, polarcontact 95, of relay 45WP in a right hand position, front contact 96 ofrelay 45WP, windings of relay 45GB, to

An energizing circuit for the correspondence relay ICE is closed fromthrough a circuit including contact 91 of switch machine control lever'ISML in a normal position, polar contact 98 of relay IWP in a righthand position, front contact 99 of relay IWP, windings of relay 'ICR, t0a Establishing a. router-T-With the system in the normal'conditionsabove outlined, the operator may govern the track switches to such newpositions as he may desire (see Fig. 1). For example, theoperation ofthe switch machine lever 23SML to .a reverse position causes the switchmachines ZS M and 3SM to operate their respective track switches.ZTS'and 3TS to reverse positions; and similarly, the operation-of theswitch machine lever 45SML causes the switch machines 48M and 5SM tooperate their respective track switches to reverse positions. Theoperation of the switch machinelever 'ISML to a reverse position causesthe switch machine ISM to operate the track switch ITS to a reverseposition. In other words, the track switches may be operated to suchpositions, as desired to set up the particular route over which it isdesired to have a train pass.

'However, the track switches are responsive to their respective controllevers only when their respective lock relays LR are energized. Forexample, if the lock relay 23LR is deenergized with front contact .HHopen (see Figs. 1 and 3A), the operation of the switch machines 28M and3 S1V I is prevented. Similarly, if the lock relay LR is deenergizedwith front contact I02 open, the operation of the switch machines 45Mand 55M is prevented in response to the lever 45SML. Likewise, thedeenergization of the lock relay "lLR' with front contact I03 open, theoperation of the switch machine ISM is prevented in response to theswitch machine lever 'ISML.

With a particular mechanical set-up of the track switches, tworoutes maybe set up thereover. In other words, a route-is considered as involvingthe direction in which a train is allowed to pass over the trackway.With the particular track layout and signaling arrangement chosen forthe embodiment. of the invention, sixteen dif- 'ferent routes may beestablished, as tabulated below. In this table, the direction of theroute is to be'considered from the signal first named to the signal lastnamed.

Route table signal I2 signal I4 signal l6 signal l2 signal l4 signal l6signal l3 signal II signal I3 signal ll o to to to to to Although alarge number of routes can be set up over the track layout chosen for,the embodimoo cngmmpowrment of the present invention, it is consideredsufiicient for an understanding of the present invention tov explain indetail only the establishment of a single route and the manner in whichanother route. maybe preconditioned while the first route is stillestablished. I For example, let us assume that the operator desires tosetup a route for the passage of a train in an east bound direction fromthe signal I3 to the signal 16. To do this, the operator first positionsthe switch machine lever 23SML in a nor,- mal position and the switchmachine levers v lSSML and 'ISML in reverse positions. Upon suchpositioning of the switch machine control levers with the system innormal condition above. explained, the switch machines immediately rerspond and operate their respective track switches to correspondinglocked positions. v The correspondence relays CR are deenergized as soonas their control levers are operated out of correspondence with theirtrack switches and are maintained deenergized during the operation ofthe switches, irrespective of the switch ma- .chine, control levermovement by reason of the unlocked condition of the track switchescausing the I deenergized condition of their respective switch positionrepeating relays WP. In other words, during the operation of a trackswitch, its switch position repeating relay WP is deenergized and theneutral contacts of said relay assume deenergized positions, but whenthe vtrack switch reaches its new position, it energizes the relay WPwith the opposite polaritywhich actuates its polarcontacts totheiropposite positions and its neutral contacts to energized picked uppositions. fIhen, as correspondence is established between the switchmachine control levers SML and their respective track switches, theircorrespondence relays CR are again energized.

In the particular case assumed, the track switches 4TS and 5TS arereversed so that as soon as they are in reverse locked positions in.correspohdence with their control lever SML, a reverse energizingcircuit is completed for the correspond-' enc'e relay 450R from througha circuit includingcontact 94 of lever 45SML in a reverse 1 Although wehave considered the complete response of the track switches to theircontrol levers prior to considering the operation of a signal lever, thesignal lever I3SL may be ope'rate'd'to a proceed or clearing positionimmediately following the operation of the switch machine control leversinvolved in the desired route (see Fig. 2)

This can be done as the correspondence relays associated with the switchmachine levers which are operated are immediately deenergized, so thatthe subsequent operation of the signal lever' I3S'L to a proceedposition can not then clear its signal by reason of the open conditionof the preliminary route selecting circuit. This will be more readilyapparent following the pointing out of the detailed circuit.

For the particular route chosen, the track switches ZTS and 3TS are innormal positions while the track switches 4TS, STS and ITS are inreverse positions. With this mechanical route set up, a preliminaryroute selecting circuit is completed which has circuit portionscorresponding to the mechanical portions of the track layout.

This preliminary route selecting circuit, together with the routeselecting circuit later to be'explained, is set up by means of thepositions of the track switches repeated by their respective relays23WP, 45WP and 'IWP. i '7 1 Assuming that the switches have respondedand that the signal lever ISSL is in a proceed position, a preliminaryroute selecting circuit is closed for the signal lever repeating relayIBSLP from through a circuit including lever 'I3SL in a proceedposition, windings'of relay I3SLP,

back contact III) of relay I3RR, polar contact III of relay 23WP in aright hand position, front contact N2 of relay 23WP, front contact" I I3of correspondence relay 230R, front contact-I I4 of correspondence relay45GB, front contact-l I5 of relay 45WP, polar contact IIBof relay 45WPin a left hand position, polar contact II1 of relay 45WP in a left handposition, front contact II8 of relay 45WP, front contact II9of relay450R, front contact I20 of relay "ICR, front contact IZI of relay 'IWP,polar contact I22 of relay 'IWP in a left hand position, back contactI23 of relay IGRR, contact I24 of lever IBSLin an at-stop position, to

As soon as this preliminary route selecting circuit is set up, a stickcircuit is closed for the relay I3SLP from througha circuit includinglever I3SL in a proceed position, windings of relay I3SLP, front contactI2Bof relay'I3SLP, to With this stick circuit closed, the energizationof the relay I3SLP is independent 'of the continued establishment of thepreliminary route selecting circuit. I 3

Before considering the results of the picking up of the signal leverrepeating relay I3SLP,it is expedient to first consider the conditionsof j thedirectional stick relays. With the relay 45WP i reverse positionin correspondence with the 6x5 i'sting reverse positions of thetrackswitches 4TS of the relay I3SLP, the pick-up and stick circuits andSTS, the contact 36 of the relay 4E8 is unshunted by contacts 38 and 39;Also, the opera-- tion' of the track switches 4TS and 5TS toreversepositions as repeated by relay 45WP'closes a shunt holding circuit forthe relay 3WS'by shunting contact 59 ofrelay 5W8 from through polarcontact 61 of relay 45WP in a. re verse position, front contact-66 tothe-wire 50. This maintains the relay 3WS energized independent'ofcontact 59 of relay -5WS.

With these conditions established with "respect to the directional stickrelays, the picking up of a signal lever repeating relay causes thosedirece tional stick relays, associated with the route me? chanically setup, to be deenergized successively (see Figs. 3A'and 3B). This, in turn,causes thelockrelays to be deenergized which locks all'of the'trackswitches in the route (see 1). g

In the case of the picking up of the contacts for the directional stickrelay 2ES are opened at back contact 26 and its contacts are released.The opening of front contact 3| of relay ZES deenergizes the pick-up andstick circuits of the relay 4ES and its contacts are released; Theopening of front contact 36 of relay 4ES opens the pick-up and stickcircuits of the relay 5E8 and its contacts are released. The opening offront contact 42 of relay 5ES deenergizes the pick-up and stick circuitsof the itscontacts are released. The opening of-front contact I9 ofrelay 2ES causes the lock relay 23LR to be deenergized, thereby lockingthe track switches ZTS and 3TS from operation in response to the controllever 23SML. Similarly, the opening of front contacts '85 and 86 ofrelay 4E8 and 5E8 deenergizes the lock relay 45LR, which locks the trackrelay IE5 and switches 4T8 and 5TS from operation in response to thecontrol lever 4-5SML. Also, the opening of front contact 89 of relay'IES deenergizes the lock relay -'ILR, which prevents the response ofthe track switch ITS to the control lever ISML;

Nowthat the track switches are looked, as indicated in the routecircuits by back contacts'on the lock'relays, the route circuit forenergizing the route relay I3RR, in serieswith the route relay IBRR isclosed (see Fig. 2). In other words, the energization of the relay I3SLPover the preliminary route selecting circuit prepares at its frontcontact I39 (see Fig. 2) the energization of the final route selectingcircuit, and at the same'time its back contact 26 (see. Fig. 3A)initiates the locking of the track switches in the route which must beaccomplished before the final route selecting circuit can be closed.

More specifically, this final route selecting circuit (see (Fig. 2) isclosed from througha circuit including front contact I30 of relay I3SLP;windings of relay I3RR, polar contact I3I onelay 23WP in a right handposition, front contact I32 of relay '23WP, back contact I33 of rel'ay23LR, back contact I34 of relay 45LR, frontcontact I35 of 45WP, polarcontact I36 of'relay 45WPjin a left hand position, polar contact I31 ofrelay 45WP in a left hand position, front contact I38 of relay 45WPpbackcontact I39 of relay 45LR, back contact I40 of relay'ILR, front contactI M of relay IWP, polar contact I42 of tov relay 'IWP in a left handposition, windingsof 10 relay IIiRRyback cont-act I43 ofrelay IBSLP, toy The energization of the route relay I3RR opens the preliminary routeselecting circuit at back ISO dependent for its energization upon'itsstick circuit closed through its front contact I26" and lever I3SL in aproceed position. Also, the energization of the route relay IBRR opensback contact I23 which prevents the energization of the relay I BSLP bythe lever IBSL moved to a proceed position.

Contemporaneous energization of. the relays I3SLP and IBRR closes anenergizing circuit for the relay I3HR (see Fig. 4A) from through acircuit including front contact I50 of relay IT, polar contact I5I ofrelay 45WP in a left hand position, front contact I52 of relay 45WP,front contact I5 3 of trackrelay 4T, front contact I54 of relay 23WP,polar contact I55 of relay 23WP in a right hand position, front contactI56 of relay 2T, front contact I51 of relay I3RR, front contact I58 ofrelay I3SLP, windings of relay I3I-1R, front contact I59 of relay I3SLP,to t The closure of front contact I60 of relay ISHR. denergizes the redlamp R of thesignal I3 and energizes the green lamp G. Thus, the routedesired to be set up by the operator is established and the train mayproceed in acceptance thereof over the trackway.

As soon as the train enters the route by occupying the track section 2,the track relay 2T is denergized which opens the pick-up circuit of therelay ZES at front contact 21, so that irrespective of the signal leverI3SL, the route will be maintained established in advance of the train.In other words, the entrance of the train into the route holds all ofthe directional stick relays deenergized in advance, although thecontrolling signal lever may be moved to a stop position and the signallever repeating relay SLP be deenergized. Then, upon the passageof thetrain over each succeeding track section, when the signal control leverI3SL has been returned to its stop position, the directional stickrelays in the rear are successively energized.

More specifically, let us assume that the train enters the detectortrack section 2 in acceptance of the signal I3 and that subsequentthereto the operator moves the signal lever I3SL to a stop position.With the lever I3SL in a stop position, both the pick-up and stickcircuits of the relay I3SLP are opened and its contacts are released.The opening of front contact I30 deenergizes the route circuit includingrelay I3RR, while the deenergization of the relay I3SLP and I3RR. bothopen the energizing circuit for the relay I3HR causing the signal I3 toagain display a stop indication by energizing its lamp R.

, It should be noted, however, that the signal I3 is put to stopimmediately upon the entrance of the train into the track section 2 byreason of the opening of front contact I56 of the track relay 2T even ifthe lever I3SL is not returned.

' The closure of back contact 26 of relay I3SLP does not allow the relayZES to pick up until the train has moved onto the track section 4 fordeenergizing the track relay 4T which prevents the energization of therelay 4138 although the relay ZES picks up by reason of the closure ofits pick-up circuit upon the-departure of the train from section 2resulting in closing front contact 21.

Similarly, the passage of the train into the track section 5 denergizes'the track relay 5T which prevents the relay 5ES from picking up althoughthe relay 4ES isenergized upon the departure of the train from the tracksection 4 allowing the energization of the track relay 4T and theresulting closure of front contact 33.

Likewise, the entrance of the train into the track section I deenergizesthe track relay IT and prevents the relay 'IES from being energized eventhough the relay 5E8 is picked up upon the departure of the train fromthe track section 5 by reason of the energization of the track 5T andthe resulting closure of its front con- 7 tact 31.

The departure of the train from the track section I on the turnout trackallows the relay 'IES to pick up by closure of contact 43.

In brief, then, the passage of the train through the route with thesignal lever put to stopas soon as the route is accepted, allows thedirectional stick relays for that route to be picked up sequentially inthe rear of the train. This sequential energization of the directionstick relays allows the sequential energization of the lock relays LRupon the passage of the train beyond the track section governing suchswitches associated with the LR relays. The passage of the train out ofthe route restores the system to its normal at rest condition asillustrated.

Various other circuits.-The above description points out in detail themanner in which route No. 3 (referring to the Route table) isestablished over the trackway and is cleared to allow the passage of atrain together with the various detailed operations involved. Thesetting. up of the remaining routes with their detailed operations maybe readily understood by analogy to the description above given.However, it is thought expedient to point out in detail the preliminaryroute selecting circuits. and the final route selecting circuitsassociated with each of the sixteen routes pointed out in the Routetable together with certain other circuits which will be set up undercertain combinations of circumstances in practice, before consideringthe preconditioning of a route. These circuits will be pointed outwithout any effort in explaining all ofthe circumstances and operationsinvolved when they exist.

The preliminary route selecting circuit for route No. 1 (see Routetable) is closed from through a circuit including lever I3SL in aproceed position, windings of relay I3SLP, back contact III) of relayI3RR, polar contact III of relay 23WP in a right hand position, frontcontact II2 of relay 23WP, front contact II3 of relay 230R, frontcontact Il of relay 450R, front contact II5 of relay 45WP, polar contactIIB of relay 45WP in a right hand position, back contact I'IZ of relayIZRR, contact I13 of lever IZSL inan'ormal at-stop position, to j Thefinal route selecting circuit for route No. 1 (see Route table) isclosed from through a circuit including front contact I30 of relayI3SLP, windings of relay I3RR, polar contact I3I of relay 23WP in aright hand position, front contact I32 of relay 23WP, back contact I33of relay 23LR, 'ba'ckcontact I34 of relay45LR, front contact I35 ofrelay IEWP, polar contact I36 of relay 45W? in a right hand position,Windings of relay IZRR, back contact 2I8 of relay IZSLP, to

The preliminary route selecting circuit for route .No. 2 (see Routetable) is closed from through a circuit including lever I3SL in aproceed position, windings of relay I3SLP, back contact I I0 of relay I3BR, polar contact III of relay 23WP in a right hand position, frontcontact II2 of relay ZSWP, front contact II3 of relay 230R, frontcontact '4 of relay 450R, frontcontact H5 of relay 4-5WP, polar contactN6 of relay 45WP in a left hand position, polar contact I ll of relay 45WP in aleft-hand position, front contact I I8 of relay 45WP, frontcontact I I9 of relay 45GB, front contact I20 of relay 10R, frontcontact I2i of relay 1WP, polar contact I22 of relay 1WP in a right handposition, back contact I66 of relay I4RR, contact I66 of lever I4SL in anormal at-stop position, to

The final route selecting circuit for route No. 2 (see Route table) isclosed from through a circuit including front contact I of relay I3SLP,windings of relay ISRR, polar contact I3I of relay 23WP in a right handposition, front contact I32 of relay 23WP, back contact I33 of relay23LR, back contact I34 of relay 45LR, front contact I36 of relay 4 5WP,polar contact I36 of relay 45WP in a left hand position, polar contactI31 of relay 45W? in a' left hand position, front contact I38 of relay45WP, back contact I39 of relay 45LR, back contact I40 of relay 1LR,front contact I M of relay 1WP, polar contact I42 of relay 1W1? in aright hand position, windings of relay I4RR, back contact I'II of relayI4SLP, to

The preliminary route selecting circuit and the final route selectingcircuit for route No. 3 (see Route table) has been pointed out in detailunder the heading Establishing a route and need not again be explained.

The preliminary route selecting circuit for route No. 4 (see Routetable) is closed from through a circuit including lever IISL in aproceed position, windings of relay I ISLP, back contact I 6I of relayIIRR, front contact I62 of relay 23CR, front contact I63 of relay 23WP,polar contact I64 of relay 23WP in a left hand position, polar contact II I of relay 23WP in a left hand position, front contact II2 of relay23WP,

front contact II3 of relay 230R, front contact II4 of relay 450R, frontcontact 5 of relay 45WP, polar contact I I6 of relay 45WP in a righthand position, back contact I1 2 of relay IZRR, contact I13 of leverI2SL in an at-stop position, to

The final route selecting circuit for route No. 4 (see Route table) isclosed from through a circuit including front contact I61 of relay IISLP, windings of relay I IRR, back contact I68 of relay 23LR, frontcontact I 69 of relay 23WP, polar contact I 10 of relay 23WP in a lefthand position, polar contact I3I of relay 23WP in a left hand position,front contact I32 of relay 23WP, back contact I33 of relay 23LR, backcontact I34 of relay 45LR, front contact I of relay 45WP, polar contactI36 of relay 45WP in aright hand position, windings of relay I2RR,backcontact 2I8 of relay IZSLP, to

The preliminary route selecting circuit for route No. 5 (see Routetable) is closed from through a circuit including lever I I SD in aproceed position, windings of relay IISLP, back contact I6I of relay IIRR, front contact I62 of relay 230R, front contact I63 of relay 23WP,polar contact I64 of relay 23WP in a right hand position, polar contactII1 of relay 45WP in a right hand position, front contact II8 of relay45WP, front contact II9 of relay 450R, front contact I20 of relay 1CR,front contact I2I of relay 1WP, polar contact I22 of relay 1WP in aright hand position, back contact I65 of relay I4RR, contact I66 oflever I 4SL in an at-stop position, to

The final route selecting circuit for route No. 5 (see Route table) isclosed from through I a circuit including front contact I61 of relayIISLP, windings of relay I IRR, back contact I68 of relay 23LR, frontcontact I69 of relay 23WP, polar contact I10 of relay 23WP in a righthand position, polar contact I31of relay 45WP in a right hand position,front contact I38 of relay 45WP, back contact I39 of relay 45LR, backcontact I of relay 1LR, front contact I4I of relay 1WP, polar contactI42 of relay 1WP in a right hand position, windingsof relay I4RR, backcontact I1I- of relay I4SLP, to I The preliminary route selectingcircuit for route No. 6 (see Route table) is closed, from through acircuit including lever IISL in a proceed position, windings of relayIISLP, back con tact I 6| of relay IIRR, front contact I62 of relay230R, front contact I63 of relay 23WP, polar contact I64 of relay 23WPin a right handposition, polar contact II1 of relay WP in a right handposition, front contact II8 of relay 45WP, front contact II9 ofrelay450R, front contact I20 of relay 1CR, front contact I2I of relay 1WP,polar contact I22 of relay 1WP in a left hand position, back contact I23of relay IBRR, contact I24 of lever I6SL in an at-stop position, to().The final route selecting circuit for route No. 6 (see Route table) isclosed from through a circuit including, front contact I61 of relay ofrelay 23LR, front contact I69 of relay 23WP,

II SLP, windings of relay IIRR, back contact I68 polar contact I10 ofrelay 23WP in a right hand position, polar contact I31 of relay 45WP ina right hand position, front contact I38 of relay 45WP, back contact I39of relay 45LR, back contact I40 of relay 1LR, front contact I4I of relay1WP, polar contact I42-of relay 1WP in a left hand position, windings ofrelay I6RR, back con lay 45CR, front contact I I3 of relay 230R, frontcontact II2 of relay 23WP, polar contact III of relay 23WP in a righthand position, back contact IIO of relay I3RR, contact I 14 of leverI3SL in'a normal at-stop position, to

The final route selecting circuit for route No. '7

(see Route table) is closed from through a circuit including frontcontact 2I8 of relay I2SLP, windings of relay I2RR, polar contact I36 ofrelay 45W'P in a right hand position, front contact I35 of relay 45WP,back contact I34 of relay 45LR, back contact I33 of relay23LR, frontcontact I 32 of relay 23WP, polar contact I3I of relay 23WP in a righthand position, windings of relay I3RR, back contact I30 of relay I 3SLP,to

The preliminary route selecting circuit for route No. 8 (see Routetable) is closed from through a circuit including lever IZSL in aproceed position, windings of relay I IZSLP, back contact I12 of relay I2RR, polarcontact I I6 of relay 45WP in a right hand position, frontcontact II5 of relay 45WP, front contact II4 of relay 45CR, frontcontact II3 of relay 230R, front contact II2 of relay 23WP, polarcontact III of relay 23WP in a left hand position, polar contact I64 ofrelay 23WP in a left hand position,'front contact I63 of relay 23WP,front contact I62 of relay 230R, back contact I6I of relay IIRR,

contact I15 of lever I ISL in an at-stop position, to I The final routeselecting circuit for route No. 8 (see Route table) is closed fromthrough a circuit including front contact 2 I8 of relay IZSLP, windingsof relay IZRR, polar contact I36 of relay 45WP in a right hand position,front contact I of relay 45WP, back contact I34 of relay 45LR, backcontact I33 of relay 23LR, front contact I32 of relay 23WP, polarcontact I 3| of re lay 23W? in a left hand position, polar contact I10of relay 23WP in a left hand position, front contact I68 of relay 23WP,back contact I53 of relay 23LR, windings of relay I IRR, back contactI61 of relay IISLP, to l The preliminary route selecting circuit forroute No. 9 (see Route table) is closed from through a circuit includinglever I4SL in a proceed position, windings of relay MSLP, back contactI65 of relay I4RR, polar contact I22 of relay 1WP in a right handposition, front contact I2I of relay 1WP, front contact I20 of relay1CR, front contact I I9 of relay 450R, front contact IIB of relay 45WP,polar contact II1 of relay 45WP in a left hand position, polar contactN6 of relay 45W]?- in a left hand position, front con tact II5 of relay45WP, front contact H4 of relay 45CR, front contact II 3 of relay 23GB,front contact II2 of relay 23WP, polar contact III of relay 23WP in aright hand position, back contact H9 of relay I3RR, contact I14 of leverI3SL in a normal at-stop position, to p The final route selectingcircuit for route No. 9 (see Route table) is closed from through acircuit including front contact I1! of relay I4SLP, windings of relayHIRR, polar contact I42 of relay 1WP in a right hand position, backcontact I4I of relay 'IWP, back contact I of relay 'ILR,

back contact I39 of relay LR, front contact I33 of relay 45WP, polarcontact I 31 of relay 45W? in a left hand position, polar contact I36 ofrelay 45WP in a left hand position, front contact I35 of relay 45WP,back contact I34 of relay 45LR, back contact I33 of relay 23LR, frontcontact I32 of relay 23WP, polar contact I3I of relay 23WP in a righthand position, windings of relay I3RR, back contact I35 of relay I3SLP,to

The preliminary roulte selecting circuit for route No. 10 (see Routetable) is closed from through a circuit including lever I4SL in aproceed position, windings of relay I4SLP, back contact I65 of relayI4RR, polar contact I22 of relay 1WP in a right hand, position, frontcontact I2I of relay 1WP, front contact I22 of relay 'ICR, front contactIIQ of relay 45CR, front contact II8 of relay 45WP, polar contact II1 ofrelay 45WP in a right hand position, polar contact I64 of relay 23WP ina right hand position, front contact I63 of relay 23WP, front contactI52 of relay ZSCR, back contact III! of relay IIRR, contact I15 of leverIISL in an at-stop position, to

of relay ILR, back contact I39 of relay 45LR,

front contact I38 of relay 45WP, polar contact I31 of relay 45W? in aright hand position, polar contact I18 of relay 23W? in a right handposition, front contact I69 of relay 23WP, back contact I68 of relay23LR, windings of relay IIRR, back contact I61 of relay IISLP, to

The preliminary route selecting circuit for route No, 11 (see Routetable) is closed from through a circuit including lever IGSL in aproceed position, windings of relay IGSLP, back contact I23 of relayIBRR, polar contact I22 of relay TWP in a left hand position, frontcontact I2I of relay lWP, front contact I23 of relay 'ICR, front contactH9 of relay 45CR, front contact H8 of relay 45WP, polar contact H1 ofrelay 455WP in a left hand position, polar contact III; of relay 45WP ina left hand position, front contact II5 of relay 45WP, front contact N4of relay IECR, front contact II3 of relay 230R, front contact I I2 ofrelay 23VVP, polar contact III of relay 23WP, back contact III] of relayI3RR, contact I14 of lever ISSL in an at-stop position, to

The final route selecting circuit for route No, 11 (see Route table) isclosed from through a circuit including front contact 643 of relayIBSLP, windings of relay IBRR, polar contact I42 of relay 1WP in a lefthand position, front contact I4I of relay 1WP, back contact I 48 ofrelay 1LR, back contact I39 of relay 4511B, front contact I38 of relay45WP, polar contact I31 of relay 45WP in a left hand position, polarcontact I33 of relay 45WP in a left hand position, front contact I35 ofrelay 45WP, back contact I34 of relay 45LR, back contact I33 of relay23LR, front contact I32 of relay 23WP, polar contact I3I of relay 23WPin a right hand position, windings of relay I3RR, back contact I31] ofrelay I3SLP, to

The preliminary route selecting circuit for route No. 12 (see "Routetable) is closed from through a circuit including lever IIISL in aproceed position, windings of relay IGSLP, back contact I23 of relayI6RR, polar contact I22 of relay 1WP in a left hand position, frontcontact IZI of relay 1WP, front contact I20 of relay 'ICR, front contactH9 of relay 450R, front contact II8 of relay 45WP, polar contact II1 ofrelay 45WP in a right hand position, polar contact IE4 of relay 23WP ina right hand position, front contact I63 of relay 23WP, front contactI62 of relay 230R, back contact I6I of relay I IRR, contact I15 of leverIISL in an at-stop position, to

The final route selecting circuit for route No. 12 (see Route table) isclosed from through a circuit including front contact I43 of relayIBSLP, windings of relay IBRR, polar contact I42 of relay 1W? in a lefthand position, front contact I4! of relay 1W1, back contact I49 of relay1LR, back contact I39 of relay 45LR, front contact I38 of relay 45WP,polar contact I31 of relay 45WP, in a right hand position, polar contactI10 of relay 23WP in a right hand position, front contact I69 of relay23WP, back contact I68 of relay 23LR, windings of relay IIRR,

back contact I61 of relay IISLP, to

The preliminary route selecting circuit for route No. 13 (see Routetable) is closed from through a circuit including lever IISL in aproceed position, windings of relay IISLP, back contact I6I of relayIIRR, front contact I62 of relay 23CR, front contactI63 of relay 23WP,

polar contact I 64 of relay 23WP in a left hand position, polar contactI I I of relay 23WP in a left hand position, front contact H2 of relay23WP, front contact II3 of relay 230R, front contact II4 of relay 450R,front contact IIE of relay 45WP, polar contact H6 of relay 45WP in aleft hand position, polar contact IITI of relay 25W in a left handposition, front contact I I8 of relay IIIWP, front contact I I6 of relay660R, front contact I23 of relay 'ICR, front contact I2I of relay 'IWP,polar contact I22 of relay TWP in a right hand position, back contactI65 of relay MRR, contact I66 of lever I SSL in an at-stop position, to

The final route selecting circuit for route No. 13 (see Route table) isclosed from through a circuit including front contact I67 of relayIISLP, windings of relay IIRR, back contact I68 of relay 23LR, frontcontact relay 33WP, polar contact I16 of relay 2 WP in a left handposition, polar contact I3I of relay 23W]? in a. left hand position,front contact I32 of relay 23WP, back contact I33 of relay 23LR, backcontact I 36 of relay 45LR, front contact I 35 of relay 45WP, polarcontact I36 of relay IIiWP in a left hand position, polar contact I3I ofrelay lSWP in a left hand position, front contact I38 of relay IEWP,back contact I33 of relay 6511B, back contact I43 of relay lLR, frontcontact HII of relay 'IWP, polar contact I42 of relay 'IWP in a righthand position, windings of relay IiRR, back contact I'II of relay MSLP,to

The preliminary route selecting circuit for route No. i l (see Routetable) is closed from through a circuit including lever II SL in aproceed position, windings of relay I ISLP, back contact I6I of relay IIRR, front contact I62 of relay 23CR, front contact I63 of relay 23WP,polar contact I64 of relay 23WP in a left hand position, polar contact III of relay 23WP in a left hand position, front contact II2 of relay23WP, front contact H3 of relay 230R, front contact II I of relay 45 CR,front contact II5 of relay QSWP, polar contact II6 of relay 46W? in aleft hand position, polar contact I II of relay 65WP in a left handposition, front contact H6 of relay IEWP, front contact H9 of relay360R, front contact I20 of relay *ICR, front contact I2I of relay IWP,polar contact I22 of relay IWP in a left hand position, back contact I23of relay I 6RR, contact I24 of lever I 6SL in an at-stop position, to

The final route selecting circuit for route N0. 14 (see Route table) isclosed from through a circuit including front contact I61 of relayIISLP, windings of relay IIRR, back contack I68 of relay 23LR, frontcontact I69 of relay 23WP, polar contact I76 of relay 23WP in a lefthand position, polar contact I3I of relay 23WP in a left hand position,front contact I32 of relay ZSVVP, back contact I33 of relay 23LR, backcontact I34 of relay 45LR, front contact I36 of relay IEWP, polarcontact I36 of relay 46W? in a left hand position, polar contact I31 ofrelay 45WP in a left hand position, front contact I38 of relay QSWP,back contact I39 of relay 35LR, back contact I40 of relay 'ILR, frontcontact III of relay 'IWP, polar contact I42 of relay IV/P in a lefthand position, windings of relay IBRR, back contact I 63 of relayIBIISLP, to

The preliminary route selecting circuit for,

route No. 15 (see Route table) is closed'from through a circuitincluding lever I ISL in a proceed position, windings of relay I ISLP,back contact I65 of relay I IRR, polar contact of relay TWP in a righthand position, front contact IIII of relay 'IWP, front contact I26 ofrelay 'ICR, front contact MB of relay 450R, front contact N8 of relayIBWP, polar contact I69 of- N1 of relaytfiWP in a left hand position,polar contact N6 of relay 35WP in a left hand position, front contact H6of relay 46WP, front contact N4 of relay 450R, front contact H3 of relay23GB, front contact II2 of relay ZZ-IWP, polar contact III ofrelayfiiIWP in a left hand position, polar contact I64 of relay 23WP ina left hand position, front contact I63 of relay 23WP, front contact I62of relay 23CR, back contact IBI of relay IIRR, contact I15 of lever'IISLin an at-stop position, to

The final route selecting circuit for route No.

15 (seefRoute table) is closed from through a circuit including frontcontact III of relay I ISLP, windings of relay I IRR, polar contact I42of relay 'IWP in a right hand position, w

23163., front contact I32 of relay 23WP, polar.

contact I3I of relay 23W1 in a left hand position, polar contact I76 ofrelay 23WP in a left hand position, front contact I69 of relay 23WP,back contact I68 of relay 231R, windings of relay IIRR, back contact I61of relay IISLP, to

The preliminary route selecting circuit for route No. 16 (see Routetable) is closed from,

(+), through a circuit including lever IGSL in a proceed position,windings of relay I6SLP, back contact I23 of relay I6RR, polar contactI22 of relay TWP in a left hand position, front contact I2I of relay'IWP, front contact I20 of relay 'ICR, front contact H9 of relay 450R,front contact IIB of relay IEWP, polar contact II! of relay 45W? in aleft hand position, polar contact II6 of relay 45W? in a left handposition, front contact H5 of relay 45WP, front contact II l of relay65GB, front contact II3 of relay 230R, front contact I I2 of relay 23WP,polar contact II I of relay 23WP in a left hand position, polar contactI64 of relay 23WP in a left hand position, front contact I63 of relay23WP, front contact I62 of relay 230R, back contact I6I of relay IIRR,contact I I5 of lever IISL in an at-stop position, to

The final route selecting circuit for route No. v:

16 (see Route table) isclosed from through a circuit including frontcontact I 53 of relay IESLP, windings of relay IBRR, polar contact I42of relay 'IWP in a left hand position, front contact I M of relay 'IWP,back contact Mil of relay 'ILR, back contact I 39 of relay 45LR, frontcontact I38 of relay ISWP, polar contact I37 of relay 46WP in a lefthand position, polar contact I36 of relay 45WP in a left hand position,front contact I35 of relay 45WP,' back contact I34 of relay 45LR, backcontact I33 of relay 23LR, front contact I32 of relay 23WP, polarcontact I3I of relay 23WP' in a left hand position, polar contact I10 ofrelay 23W? in a left hand position, front contact I69 of relay 23WP,back contact I68 of relay 23LR, windings of relay I IRR, back contactI61 of relay IISLP, to

As previously pointed out, the lever repeating relay I3SLP has a stickcircuit closed once its contacts are picked up by reason of itsenergization over a preliminary route selecting circuit, so long as thelever I3SL is maintained in a proceed position to close the stickcircuitthrough front contact I26. A similar stick circuit is closed for each ofthe remaining signal lever repeating relays SLP, as each of these relayshave suitable stick contacts.

More specifically, the relay IISLP has a stick contact I16 for closingits stick circuit with the lever IISL in a proceed position wheneverthis relay IISLP has been picked up over a preliminary route selectingcircuit.

The relay I2SLP has a stick contact III for closing its stick circuitwith the lever I 2SL in a proceed position whenever this relay I2SLP hasbeen picked up over a preliminary route selecting circuit.

The relay I ISLP has a stick contact I19 for closing its stick circuitwith the lever IQSL in a proceed position whenever this relay I4SLP hasbeen picked up over a preliminary route selecting circuit.

The relay IGSLP has a stick contact I19 for closing its stick circuitwith the lever IGSL in a proceed position whenever this relay IBSLP hasbeen picked up over a preliminary route selecting circuit.

The energizing circuit for the signal controlling relay I3HR for'routeNo. 1 is closed from through a circuit including polar contact II ofrelay 45WP in a right hand position, front contact I52 of relay 45WP,front contact I53 of relay 4T, front contact I54 of relay 23WP, polarcontact I55 of relay 23WP in a right hand position, front contact I59 ofrelay 2T, front contact I5'I of relay I3RR, front contact I58 of relayI3SLP, windings of relay I3HR, front contact I59 of relay I3SLP, to

The energizing circuit for the signal controlling relay I3HR for routeNo. 2 is the same as explained for route No. 3 in the above descriptionunder the heading Establishing a route.

The energizing circuit for the signal controlling relay IIHR, for routeNo. 4 is closed from through a circuit including polar contact I5I ofrelay 45WP in a right hand position, front contact I52 of relay 45WP,front contact I53 of relay 4T, front contact I54 of relay 23WP, polarcontact I 55 of relay 23WP in a left hand position, polar contact I85 ofrelay 23W? in a left hand position, front contact I84 of relay 23WP,front contact I89'of relay 3T, front contact I81 of relay IIRR, frontcontact I88 of relay IISLP, windings of relay III-IR, front contact I89of relay IISLP, to

The energizing circuit for the signal controlling relay I II-IR, forroute No. 5 is closed from through a circuit including front contact I89of relay IT, front contact I8I of relay 45WP, polar contact I82 of relay45WP in a right hand position, front contact I83 of relay 5T, polarcontact I85 of relay 23WP in a right hand position, front contact I84 ofrelay 23WP, front contact I 86 of relay 3T, front contact I81 of relayIIRR, front contact I88 of relay IISLP, windings of relay III-IR, frontcontact I89 of relay IISLP, to

The energizing circuit for the signal controlling relay I I HR for routeNo. 6 is the same as for route No. 5 as the track circuit in the rear ofsignal I6 is the same as in the rear of signal I4.

The energizing circuit for the signal controlling relay I ZHR for routeNo. '7 is closed from through a circuit including polar contact I9I ofrelay 23WP in a right hand position, front contact I92 of relay 23WP,front contact 193 of relay 2T, front contact I94 of relay 4T, wire I95,front contact I96 of relay I2RR, front contact I91 of relay I2SLP,windings of relay IZHR, front contact I98 of relay IZSLP, to 1 Theenergizing circuit for the signal controlling relay I2I-IR. for routeNo. 8 is closed from through a circuit including front contact I99 ofrelay 3T, polar contact I9I of relay 23WP in a left hand position, frontcontact I92 of relay 23WP, front contact I93 of relay 2T, front contactI94 of relay 4T, Wire I95, front contact I99 of relay IZRR, frontcontact I9! of relay I2SLP, windings of relay IZHR, front contact I98 ofrelay IZSLP, to

The energizing circuit for the signal controlling relay I4HRfor routeNo. 9 is closed from through a circuit including polar contact I9I ofrelay 23WP in a right hand position, front contact I92 of relay 23WP,front contact ZIB of relay 2T, front contact 2II of relay 4T, polarcontact 29I of relay 45WP in a left hand position, front contact 292 ofrelay 45WP, front contact 293 of relay 5T, front contact 294 of relaylT, wire 295, front contact 29! of relay I4RR, front contact 298 ofrelay I4SLP, windings of relay I4HR, front contact 299 of relay I4SLP,to

The energizing circuit for the signal controlling relay I4HR for routeNo. is closed from through a circuit including front contact 299 ofrelay 3T, polar contact 29I of relay 45WP, in a right hand position,front contact 292 of relay 45WP, front contact 293 of relay 5T, frontcontact 294 of relay IT, wire 295, front contact 291 of relay MR-R,front contact 298 of relay I4SLP, windings of relay MHR, front contact299 of relay I4SLP, to

The energizing circuit for the signal contro-lling relay I 9BR for routeNo. 11 is closed from through a circuit including polar contact I9I ofrelay 23WP in a right hand position, front contact I 92 of relay 23WP,front contact 2I6 of relay 2T, front contact 2II of relay 4T, polarcontact 29I of relay 45WP in'a left hand position, front contact 292 ofrelay 45WP, front contact 293 of relay 5T, front contact 294 of relayIT, wires 295 and 2| 5, front contact 2H of relay IBRR, front contact 2I2 of relay I9SLP, windings of relay IBHR, front contact 2I3 of relayIBSLP, to

The energizing circuit for the signal controlling relay IGHR for routeNo. 12 is closed from through a circuit including front contact 299 ofrelay 3T, polar contact 29I of relay 45WP, in a right hand position,front contact 292 of relay 45WP, front contact 293 of relay 5T, frontcontact 294 of relay IT, wires 295 and M5, front contact 2I I of relay IERR, front contact 2! 2 of relay IGSLP, windings of relay IEHR, frontcontact 2I3 of relay IBSLP, to

The energizing circuit for the signal controlling relay IIHR. for routeNo. 13 is closed from through a circuit including front contact I59 ofrelay IT, polar contact I5I of relay 45WP in a left hand position, frontcontact I52 of relay 45WP, front contact I53 of relay 4T, front contactI 54 of relay ZBWP, polar contact I55 of relay 23WP in a left handposition, polar contact I 85 of relay 23WP in a left hand position,front contact I84 of relay 23WP, front contact I86 of relay 3T, frontcontact I81 of relay IIRR, front contact I98 of relay IISLP, windings ofrelay III-IR, front contact I99 of relay IISLP, to

The energizing circuit for the signal controlling relay IIHR for routeNo. 14 is the same as for route No. 13.

The energizing circuit for the signal controlling relay I IHR for routeNo. is closed from through a circuit including front contact I90 ofrelay 3T, polar contact IQI of relay 23WP in a left hand position, frontcontact I92 of relay 23WP, front contactZIS of relay 2T, front contact2I'I of relay 4T, polar contact 2M of relay WP in a left hand position,front contact 292 of relay tEiWP, front contact 203 of relay 5T, frontcontact 264 of relay 'lT, wire 205, front contact 20'! of relay MRR,front contact 2838 of relay IGSLP, windings of relay MHR, front con tact269 of relay MSLP, to

The energizing circuit for the signal controlling relay itHR for routeNo. 16 is closed from through a circuit including front contact ISQ ofrelay 3T, polar contact iill of relay MVP in a left hand position, frontcontact I92 of relay 23WP, front contact M6 of relay 2T, front contact2!? of relay 4T, polar contact Zili of relay IEWP in a left handposition, front contact 232 of relay til VP, front contact 2133 of relay5T, front contact 264 of relay 1T, wires 295 and 215, front contact 2Hof relay ifiRR, front contact 292 of relay IESLP, windings of relay IGHR, front contact 2I3 of relay IBSLP, to

It has been pointed out above that the red indicating lamp R of thesignals H, 52, I3, is and it are energized so as to give a danger orstop indication under normal conditions. This is accomplished by reasonof the closure of their energizing circuits through back contacts oftheir corresponding signal controlling relays HR. The energization ofthe respective signal controlling relays HR deenergizes the respectiveindicating lamps R. and energizes through front contacts the respectiveindicating lamps G.

More specifically, the relay IIHR, controls the signal H by its contact99; the relay IEHR controls the signal I2 by its contact I99; the relayI SHRcontrols the signal I3 by its contact I60; the relay MHIR controlsthe signal It by its contact 250; and therelay IfiI-IR controls thesignal It by its Contact 2M.

Preconditioning of a. route.'In the description of the presentinvention, it is desired to employ the word preconditioning? inconnection with the positioning of the control levers for a route priorto the actual establishment of that route which is prevented from beingestablished until a route with which it conflicts ceases to conflict.

In other words, the operator may set up one route and immediatelythereafter position the control levers for another route which conflictswith the first route, but the first route is not actually set up untilthe second route ceases to confiict with it. Thus, the second route maybe said to be preconditioned during that time in which the first routestill conflicts with it.

To describe such a situation, We may assume that the operator hasestablished a first route (route No. 3 as previously described) byclearing signal I3 for the passa'ge'of a train in an eastbound directionover the track switch ZTS in a normal position, and the track switches4T5, 5T5 and ITS in reverse positions. Under these conditions, the leverrepeating relay QSSLP is energized together with the route relay I BRRso that the relay EEHR is energized clearing the signal I3. The leverrepeating relay lBSLl? is maintained energized independent of itspreliminary route selecting circuit and is held energized dependent uponits stick circuit including the signal lever ISSL in a proceed position.Also, with the route relay I3RR energized and the directional stickrelays for that route deenergized, the

lock relays ZSLR, 451113, and ELR are deenergized,

, as previously explained.

With the lock relay iLR deenergized, opening front contact I82 in theswitch machine control circuit, the switch machine control lever fist/ILThe lever QSSML returned to a normal position deenergizes itscorrespondence relay 458R. Althoughthe signal lever I iSL is in aproceed position, the lever repeating relay liSLP can not pick up as itspreliminary route selecting circuit is not yet closed.

When the first train accepts the route No. 3 established upon theclearing of signal it, the operator may return the signal lever IESLP toa stop position. This allows the lock relays 23LR and fieLR to be pickedup after the train passes the corresponding track sections associatedwith the corresponding switches. In other wordsgas soon as the train isonthe track section '7 and is entirely off the track section 5, theswitch ma chines 45M and 58M respond to the control leve-r 458m in anormal position and operate the track switches lTS and 5T8 to normalpositions. As soon as the track switches 5T8 and 5T8 are in normalpositions, the switch. repeating relay 45WP is operated intocorrespondence therewith and the correspondencerelay dtCR is energized.

This completes the preliminary routeselecting circuit for the leverrepeating relay IISLP for route No. 6 as pointed out above. Thisenergization of relay HSLP causes the tumble-down of the directionalstick relays 3E3, 5E3 and 'lES by the opening of back contact 46 ofrelay l ISLP. It is to be noted, however, that the relay 'lES mayalready be down as the first train which accepted the route No. 3 maynot yethave passed off from r the track section '7. However, thetumble-down directional stick relays are all I deenergized for the routeNo. 6. Thus, the route relay i iRR may be energized in series with theroute'relay itRR through the final route selecting circuit for route No.6 as given above.

As the second train passes through this route No. 6, the track switchesare sequentially re.- leased as will be understood by analogy to thedescription of the route No. 3 above described;

A facing point route preconditioned-In the above explanation ofpreconditioning, the route preconditioned entered the first routethrough a The energization of the relay I IHR closes trailing point moveof the track switch 5T5, so

that the preliminary route selecting circuit for route No. 6 as well asits final route selecting circuit was opened at polar contacts II! andI37 of relay QEWP until the switches ATS and ETS were operated intocorrespondence with the lever 45SML in a normal position, which does notbring out the particular usefulness of the correspondence relay 450R,for example,

Assuming only the route No. 1 to be set up, then if the operator shouldmove the signal lever HSL to a proceed position, without first operatingthe switch machine lever 23SML to a reverse position, the parallel routeNo. would be set up allowing a train to pass on to the signal 14. Forexample, assuming the lever 23SML to still be in a normal position, itwill be apparent that the preliminary route selecting circuit for routeNo. 5 may be closed for the relay HSLP with the signal lever HSL in aproceed position, as above pointed out.

However, in preconditioning the desired route No. 4 so as to have asecond train follow the first train which is just passing over route No.l, the operator moves the switch machine control lever 23SML to areverse position prior to the operation of the signal control lever HSLto a proceed position. This causes the de-energization of thecorrespondence relay 230R which opens the preliminary route selectingcircuits for routes No. 5 and No. 4 at its front contact I62, therebypreventing an undesired parallel route to be set up from signal H tosignal M or H5.

The reversal of the track switches ZTS and 3T3 upon the passage of thefirst train from track section 2 to track section 4 operates the relay23WP to a reverse position followed by the energization of the relay230R. This completes the preliminary route selecting circuit for routeNo. a to energize the relay IISLP.

The energization of the relay HSLP causes the tumble-down of thedirectional stick relays for this route No. 4 as will be readilyunderstood by analogy to the description already given. As soon as thelock relays have assumed de-energized positions in response to thetumble-down of the directional stick relays, the final routeselecting'circuit for route No. 4 is closed and energizes the relay HRR.With the relays HSLP and RR both picked up, the relay III-IR isenergized over its selecting circuit for route No. 4, as above pointedout. This clears the signal II and the second train can proceed over theroute No. l from signal ll to signal I2 with the usual operations of theautomatic signaling.

System modified according to Fig. 5.-The system of the presentinvention, as disclosed in preceding figures, may be modified inaccordance with Fig. 5 to provide a system wherein the operator does nothave to return the signal lever SL of a first route to a stop positionin order to allow a preconditioned second route to automatically haveits switches operated to proper positions followed by the clearing ofits signal.

In accordance with the modification, the routes are established aspreviously described, but the acceptance of a route by a train puts itsgoverning signal to stop, and is held at-stop by a stick repeating relayof the track section in the rear of that signal irrespective of whetherits signal control lever is moved to stop or left in its proceedposition. track section immediately in the rear of the signal permitsthe directional stick relays governing The stick repeating relay of thiscircuit closed from through a circuit including back contact 253 ofrelay HSLP, windings of relay 3TPS, front contact 254 of relay 3T, to Anauxiliary stick circuit for the relay 3TPS is closed from through acircuit including front contact 255 of relay BTPS, windings of relay3TPS, front contact 254 of relay 3T, to

The directional stick relay 3E8 is controlled by the lever repeatingrelay HSLP through back contact 45 as described in connection with Fig.3. The signal controlling relay IIHR is norally de-energized, so thatits back contact 9i! completes the energizing circuit of the red lamp Rof the signal 3!.

To establish a route, with the system modified in accordance with Fig.5, the operator moves the signal control lever such as the signal leverHSL, to a proceed position subsequent to the proper positioning of thetrack switches in the route. This causes the energization of thepreliminary route selecting circuit for the desired route including therelay HSLP, for example, which opens back contact 46 and causes thedirectional stick relays for that route to be deenergized. When the lockrelays in the route have been dropped away and the final route selectingcircuit is completed, the relay HRR is energized closing its frontcontact I87. This completes an energizing circuit for the relay 5 IHR.from through a circuit including front contact 25l of relay 3TPS, frontcontact 259 of relay 3T, front contact it! of relay HRR, front contact688 of relay ilSLP, windings of relay liHR, front contact I83 of relayHSLP, to The closure of front contact 90 energizes the green repeated bythe relay 3TPS, as the front contact 254 included in its pick-up andstick circuits is opened. In other words, while the lever IESL is in aproceed position and the relay HSLP is picked up, the relay 3TPS is heldenergized by its stick circuit, which stick circuit is opened upon thepassage of a train through the track section 3. The opening of frontcontact 250 of relay 3T causes the relay HHR to be de-energized as wellas the opening of front contact 25! of relay ETPS, but the front contact25| of relay 3TPS maintains the relay III-IR de-energized even after thetrain passes beyond the track section 3, as the closure of front contact254 of relay 3T does not cause the relay 3TPS to be picked up unless thelever HSL has been returned to a stop position allowing the closure ofback contact 253 of relay HSLP.

' Thus, assuming that the lever HSL has been left in a proceed position,the signal H is maintained at-stop upon the passage of a train by therelay 3TPS remaining de-energized. While the train is on the tracksection 3, the directional stick relay 3E5 is maintained de-energized byreason of open front contact t! but upon the passage of the train beyondthe track section 3 over whatever route is established, the closure offront contact 41 allows the direction stick relay tES to be picked up bya circuit closed from through a circuit including back contact 25! ofrelay 3TPS, front contact 41 of relay 3T, windings of relay 3ES, to

In other words, the passage of the train through the track section 3 andover the remainder of the route allows the directional stick relays forIII that route to be successively picked up in the rear because of theclosure of back contact 25l even though the signal lever for that routeis in a proceed position and the back contact 46 of relay IISLP is open.

This restoration of the directional stick relays for the route of courseallows the picking up of the lock relays for the switches so that anyprepositioned switch levers may govern their switches in that route assoon as they are released and a preconditioned route may beautomatically established even though the operator has not returned thesignal lever for the first route to an at stop position.

In brief, the application of the relay 3TPS provides that the signal llis made a stick signal and when this stick feature is applied to asignal, the directional stick relays governed by that signal may bereleased upon the passage of a train through the route. It should beunderstood that the features of Fig. 5 may be applied to one or all ofthe signals of an interlocking plant, as disclosed in accordance withthe present invention.

SUMMARY The operation of an interlocking system provided in accordancewith the present invention comprises in general the setting up of aroute mechanically by operating the track switches to such positions, asdesired, followed by the movement of the proper signal control lever toa clear or proceed position. The movement of the signal lever to a clearor proceed position causes the energization of its lever repeating relayproviding a preliminary route selecting circuit is properly prepared bythe switch repeating relays and the correspondence relays which requirethat the track switches in the desired route must be in correspondencewith the switch control levers at that time. If the preliminary routeselecting circuit is completed and the signal lever repeating relay ispicked up, the directional stick relays for that route are de-energiaedsuccessively, thereby looking all of the track switches in that routefrom operation by their switch lever.

When the track switches in the route have been locked, the final routeselecting circuit is closed, which allows the signal controlling relayto be picked up subject to trafiic conditions.

Once a route has been established by the clear ing of its signal, thetrack switches in that route cannot respond to their switch levers, sothat the switch levers may be moved to such positions, as desired, inorder to precondition a second route. As the preliminary route selectingcircuit for the route already cleared is only temporarily effective atthe time of the clearing of that route,

the change in the position of the switch levers and the de-energizationof the correspondence relays does not eifect the governing of the routealready set up.

The passage of a train through the first route set up, beyond the pointat which the second route conflicts therewith, allows the second routeto be established by the clearing of its signal. This is made effectiveby either the putting to stop of the signal lever for the first route,or automatically upon the passage of a train putting such signal to stopand holding it at-stop, either method of which may be employed inaccordance with the present invention. i

In other words, an interlocking'system has been described which hasroute circuits corresponding to the actual track layout which circuitscan-not be completed until the track switches in the route are incorrespondence with their switch control levers and have been locked,although such locking occurs subsequent to the actuation of the signalcontrol lever for that route.

In accordance with the present invention, each signal may be preferablyprovided with suitable approach locking means having associatedtherewith suitable time releasing means, as above pointed out, althoughsuch means have not been described in detail. Various other featuresemployed in connection with approach locking and interlocking systemsmay be adapted to or employed with the present interlocking systemproposed herein without effecting the scope of the present invention. c

Having thus shown and described an interlocking system as one specificembodiment of the present invention, it is desired to be understood thatthis form is selected to facilitate in the disclosure of the inventionrather than to limit the number of forms which it may assume; and, it isto be further understood that various modifications, adaptations andalterations may be applied to the specific form shown to meet therequirements of practice, without in any manner departing from thespirit or scope of the present invention except as limited by theappended claims.

What we claim is:

1. In a trafiic controlling system for railroads; a track layoutcomprising a plurality of track switches for mechanically setting up aplurality of routes; signals for governing traffic over each of saidroutes, each of said signals being capable of; giving stop or proceedindications; control levers for said track switches and said signals; apreliminary route circuit for each of said routes, a particularpreliminary route circuit being closed by the signal lever for thatroute when and only when the track switches in that route and theirrespective control levers are in corresponding positions; means forlocking the track switches in a particular route when said preliminaryroute when the track switches in that route are locked;

and means for causing the signal for a particular route to indicateproceed when and only when said final route circuit for that route isclosed,- said means being independent of said preliminary route circuitif said preliminary route circuit has been momentarily energized, andsaid means being dependent upon said signal lever for that route.

2. In a traffic controlling system for railroads, a track layoutcomprising a plurality of track switches for setting upa plurality ofmechanical routes through said track layout; signals for gov erningtrafiic over each of said routes, said signals normally indicating stopbut being capable of indicating proceed; a switch lever for each of saidtrack switches; a signal lever for each of said signals; a preliminaryroute circuit for each of said routes conforming to its mechanicalcounterpart, said preliminary route circuit for a particular route beingclosed by the signal lever for the corresponding route when and onlywhen the track switches in that route are in positions corresponding tothe positions of their respective switch levers; locking means forlooking the track switches in a particular route when said preliminaryroute circuit for that route has been closed; a final route circuit foreach of said routes

